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Description

BEST 1ST FULL SUSPENSION

The perfect upgrade for adventurous kids (ages 7-11) ready to take on bigger challenges. Its full-suspension design with 120mm travel is built to handle rocks, roots and jumps. Plus, it's mullet-compatible, so you can upgrade to a 26" front wheel as your child grows, extending the life of the bike and their riding progression!

VALUE MEETS PERFOMANCE

Built around a durable alloy frame, the D24 features custom-tuned air suspension for lighter riders, offering superior performance that can be easily adjusted as they grow. Even better, the D24 now comes with hydraulic disc brakes, providing ample stopping power, while the microSHIFT 1x8 drivetrain offers plenty of range for tough climbs and simple, easy shifting.

A TRUSTED BRAND

Polygon is a factory-direct brand with over 30 years of experience crafting high-performance bikes at competitive prices. Vertically integrated manufacturing ensures quality and cost savings. Their mountain bikes have been tested on the world stage at events like Redbull Rampage and the World Cup circuit, boasting a 5-year frame warranty for peace of mind.

AIR SUSPENSION

The Suntour Raidon 32 fork and Raidon R rear shock offer 120mm of travel, soaking up bumps, providing a smooth, controlled ride on any trail. The air springs can be easily adjusted to match your child's weight and riding style.

MICROSHIFT 1x8 DRIVETRAIN

The microSHIFT Acolyte 1x8 drivetrain delivers smooth, reliable shifting and the 12-42t cassette offers plenty of range to get up steep climbs. Thanks to the clutch rear derailleur, there is no clunking or rattling from the drivetrain and less dropped chains!

HYDRAULIC DISC BRAKES

Tektro hydraulic brakes provide tonnes of power and all weather performance. Levers specifically designed for small hands are easy to reach and will save any rider in a sticky situation.

UPGRADABLE

Kids progress quickly and that means upgrades, thankfully the D24 frame is dropper post ready and the wheels come pre-taped for tubeless from the factory, making all future upgrades a breeze!

Components

FRAMESET
FRAME
ALX XC Trail Kids 6061 Aluminum Frame, 120mm Travel, Internal Routed Gear & Dropper Cables, Tapered Headtube, 73mm Threaded BB, ISCG05 Chain Guide, 142x12mm Thru-Axle
SUSPENSION
FORK
Suntour Raidon 32, Air Spring, 120mm Travel, Rebound, Lockout, Q-LOC2 Axle 15x100mm
SHOCK
Suntour Raidon R, Air Spring, Rebound, Custom Tune
DRIVETRAIN
REAR DERAILLEUR
Microshift Acolyte RD-M5185M, Medium Cage, Clutch
SHIFTER
Microshift Acolyte Trigger SL-M7180M, 1x8-speed
CRANK
Prowheel C10Y-NW, 30T, 140mm
CASSETTE
Microshift Acolyte CS-H083, 8-speed, 12-42T
CHAIN
KMC Z8
BRAKES
FRONT BRAKE
Tektro HD-J285, Hydraulic Disc, 160mm Rotor
REAR BRAKE
Tektro HD-J285, Hydraulic Disc, 160mm Rotor
WHEELS
REAR HUB
Entity Sealed Beaing, 12mm Thru-Axle, 142mm spacing
RIM
Entity X15 Disc, 32H, Internal Width: 24mm, Tubeless Tape Installed
TYRE
Vee Tire Flow Snap 24X2.4", Natural Wall, Wire Bead, Tackee Compound (Non-Tubeless)
MAX TYRE SIZE
F: 26” | R: 24”
CONTACT POINTS
HANDLEBAR
Entity Sport, Alloy, Width: 640mm, Rise: 20mm
SADDLE
Entity MTB Kids
SEATPOST
Entity Sport, Alloy, 30.9x250mm
STEM
Entity Sport, Alloy, Length: 40mm, BB: 31.8mm

Geometry

  One Size
Rider Height 4'2"–4'11"
Frame Stack (A) 534.1
Frame Reach (B) 350
Head Tube Length (C) 90
Head Tube Angle (D) 66
Seat Tube Angle (E) 73.5
Effective Seat Tube Angle 75
Seat Tube Length (F) 317
Effective Top Tube (G) 493.1
Bb Height (H) 303.5
Bb Offset (I) 10 (DROP)
Chainstay Length (J) 400
Wheelbase (K) 1028.2
Standover Height (L) 598.4
Minimum Saddle Height 705
Maximum Saddle Height 830
Maximum Seat Post Insertion Depth 200mm
Crank Length 140
Front Travel 120

* All lengths in mm

 

  Technical Information
Front Travel 120
Rear Travel 120
Maximum Tyre Width 2.4"
Maximum Chainring Size 32T
Rear Shock Spec E2E 190x51, M8x25 Hardware
Headset Spec ZS 44/28.6 | ZS 56/40
Spokes Front L: 232, R: 232
Spokes Rear L: 232, R: 230

Assembly

Your bike needs minor assembly before riding; use the tools and videos included.

As a guide, it'll take 10-40min depending on whether you're an experienced bike assembler or have little to no mechanical experience.

Side Note: Your cables will stretch during the initial bed-in period and must be adjusted by an experienced mechanic around 150km of riding.

Step 1

Unboxing Your Bike

Step 2

Bike Fit Setup

Step 3

https://cdn.shopify.com/videos/c/o/v/518f490ce56d4dc1af5f422abe2bacbf.mp4

Customer Reviews
4.9 Based on 55 Reviews
5 ★
96% 
53
4 ★
2% 
1
3 ★
2% 
1
2 ★
0% 
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1 ★
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Customer Photos
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LM
03/19/2025
Lachlan M.
Australia

Sturdy little Machine, great service A+

Was nervous about buying a bike online without test riding first. No need to be. The perfect bike for my son to go to the next level with his riding. Well built to a high quality, adjustable to suit my son’s height and weight, sturdy frame. Expecting quite a few years of great riding out of it. Very impressed with the prompt delivery as well. Thanks bike sales, great service, really good little product. As described, I’ve had no surprises at all which is a nice change 😃👍

JS
03/02/2025
joseph s.
United States

Birthday

The bike came as expected and easy to put together so I took grandson out to ride at the state park and the bike worked flawless he enjoyed the bike and rode for about 3 hours about 7 miles first ride at the state park

F
11/19/2024
feliks
Australia

polygon sisiku d24

perfect

NR
05/06/2024
Nate R.
United States

Great intro to full suspension

This bike has really elevated my 8 year olds skills! Only complaint is that it’s a bit heavy since he’s only 52lbs. I love the ability to swap wheels for 26” when he grows some more. Bike is very stable and suspension is just about perfect for him.

BikesOnline Australia Polygon Siskiu D24 - Kids Mountain Bike Review